Anchor apparatus and method

ABSTRACT

Anchor apparatuses and methods for anchoring a tool within a wellbore are disclosed. An anchor apparatus can include an operator, such as an electrical motor, a hydraulic source, or other similar sources of motion, to cause movement of a rod between a first and second position. A plurality of arms pivotally secured to the apparatus are movable between a retracted position and an extended position. Movement of the rod from the first position to the second causes the rod to pivot the arms toward the extended position. Computer instructions can be utilized to cause automatic retraction of the arms upon receipt of a command after a selected interval of time has lapsed to prevent attempted removal of the apparatus while the arms are extended. The anchor apparatus can also include a frangible member provided with a selected tolerance to enable removal of the apparatus without retraction of the arms.

FIELD

The present invention relates, generally, to anchor apparatuses andmethods for anchoring and/or maintaining a position of a tool within awellbore.

BACKGROUND

When producing a well, or performing other downhole operations, a largevariety of extreme pressures and other forces within the wellboreenvironment affect the apparatuses lowered into the well, as well as thetool strings, wirelines, slicklines, or other conduits used to lowerthese apparatuses. Additionally, actuation of various downhole tools cancause changes in downhole pressure, and can create forces thatcatastrophically entangle or otherwise badly damage the tools and theirassociated conduits. For example, when producing a well, a perforatinggun is typically actuated to create multiple perforations within asegment of casing and sections of the borehole external to the casing.This operation can create a region of high pressure at the site of theperforation, which can forcibly move the perforating gun in an upholedirection, breaking and/or entangling the wireline, slickline, toolstring, or other conduit used to lower the perforating gun. Remedialfishing and/or clean-up operations to correct such a situation can beextremely costly and time consuming and can halt production of a wellfor a significant length of time.

To prevent undesired movement of a tool caused by downhole forces,anchor devices are typically engaged with a perforating gun or otherperforating apparatus prior to lowering the apparatus into the wellbore.Additionally it is often desirable to retain other types of tools, suchas production logging tools, at a generally fixed location within awellbore while flowing the well pressure toward the surface.Conventional anchor devices typically include a body sized to passthrough any restrictions between the surface and the desired positionfor the tool, having one or more arms or slip segments movable between aretracted position within the body and an extended position to engagethe wellbore. Most anchor devices are mechanical in nature, having armsor slip segments that move outward to engage the wellbore responsive tosudden or significant uphole velocity, preventing further upholemovement before significant damage is incurred. Other anchor devices useactuatable sleeves or mandrels to physically bias arms or slip segmentsin an extended position to engage the wellbore prior to actuating theperforating apparatus.

A need exists for an anchor apparatus and method for anchoring and/ormaintaining a position of a tool within a wellbore that providesimproved reliability and simplicity over conventionally available anchordevices, while incorporating use of back-up methods of removal whenstandard disengagement from the internal surface of a wellbore isunsuccessful or impossible, and use of automatic safety features forpreventing attempted retrieval of the anchor apparatus when engaged withthe interior surface of a wellbore.

The present invention addresses these needs.

BRIEF DESCRIPTION OF THE DRAWINGS

In the detailed description of the embodiments of the inventionpresented below, reference is made to the accompanying drawings, inwhich:

FIGS. 1-14 depict a partial cross-sectional view of an embodiment of ananchor apparatus usable within the scope of the present disclosure. Eachsuccessive figure depicts a portion of the embodiment of the anchorapparatus disposed generally adjacent to that shown in the preceding andfollowing figures.

FIG. 15A depicts an embodiment of a rod, piston, and/or mandrel usablewithin the anchor apparatus of FIGS. 1-14 for biasing of the arms toengage a wellbore.

FIGS. 15B and 15C depict embodiments of movable arms usable within theanchor apparatus of FIGS. 1-14 for engagement with an interior surfaceof a wellbore.

FIG. 16A depicts a diagrammatic view of an embodiment of an anchorapparatus usable within the scope of the present disclosure disposed ina disengaged position.

FIG. 16B depicts the anchor apparatus of FIG. 16A disposed in an engagedposition.

The depicted embodiments of the invention are described below withreference to the listed Figures.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Before explaining the disclosed embodiments of the invention in detail,it is to be understood that the present invention is not limited to theparticular embodiments depicted or described, and that the invention canbe practiced or carried out in various ways.

The preset invention relates, generally, to anchor apparatuses andmethods for maintaining a position of a tool, such as a perforating,cutting, or isolation apparatus, a production logging apparatus, orother types of downhole tools, within a wellbore, before, during, andafter actuation of the tool, and during production of a well.Embodiments of the anchor apparatus can include a tubular body havingone or more connections, such as a threaded pin or box end, forengagement with one or more tools, and an internal rod, piston,cylinder, and/or mandrel moveable within the body. An operator, whichcan include a hydraulic source, an electrical motor, or any other sourceof locomotive force, including pneumatic, fluid-driven, and/ormechanical sources, can be in operative communication with the rod, suchthat actuation of the operator causes movement of the rod within thetubular body between a first position and a second position.

A plurality of arms pivotally secured to the tubular body are movablebetween a retracted position within or proximate to the body, and anextended position for engagement with the interior surface of awellbore. A biasing member, such as one or more springs, can be providedin association with the arms, such that the arms are normally biasedtoward their retracted position. Movement of the rod from the firstposition to the second position causes contact between the rod and thearms, such that the arms are urged into their extended position forengagement with the interior surface of the wellbore. While the rod isretained in the second position, the arms can be maintained in theirextended position against the force exerted by the biasing member.Forces caused by actuation of the tool and/or other forces within thewellbore are thereby unable to undesirably move the anchor apparatus orthe attached tool due to the engagement between the arms and theinterior surface of the wellbore. When retrieval of the anchor apparatusand/or the tool is desired, the arms can be retracted by actuating theoperator to move the rod axially from the second position to the firstposition, such that the biasing member can return the arms to theirretracted position.

In an embodiment of the invention, a frangible member, such as a shearring, screw, and/or pin, can be provided at one end of the arms, thefrangible member being provided with a preselected tolerance thatexceeds forces within the wellbore, but is less than a force sufficientto damage the arms. When it is undesirable, unsuccessful, or impossibleto cause retraction of the arms from the interior surface of thewellbore, sufficient uphole force can be applied from the surface, inany manner known in the art, to shear the frangible member, enablingretrieval of at least a portion of the anchor apparatus and removal ofthe wireline, slickline, tool string, or other carrier from thewellbore.

Embodiments of the invention can further include circuitry within theanchor apparatus, in communication with a processor, such that theprocessor causes actuation of the operator to move the rod, to therebyextend and retract the arms, responsive to receipt of a command. Forexample, a command from the surface can be transmitted to the processorusing a wireline, to selectively cause extension and/or retraction ofthe arms. Alternatively, a slickline memory tool or similar downholeapparatus can be sued to cause actuation of the anchor apparatus, suchthat no communication or signal to or from the surface is required. Forexample, a memory tool can be programmed to cause actuation of theanchor apparatus when the tool is lowered to a preselected downholelocation where it is desirable to engage in logging operations,perforating, cutting, or other downhole operations. In other embodimentsof the invention, a memory tool can be programmed to cause actuation ofthe anchor apparatus when pressure from the well becomes equal to orexceeds the weight of the tool string or other carrier.

Further embodiments of the invention can include use of an automaticsafety feature. When performing certain downhole operations, asignificant length of time can elapse between extension and retractionof the arms of the anchor apparatus. It is common for a human operatorto become unaware of the position of the arms, and attempted removal ofthe anchor apparatus while engaged with the interior surface of thewellbore can cause unnecessary damage to the anchor apparatus andassociated components. In an embodiment of the invention, computerinstructions in communication with the processor can instruct theprocessor to monitor the elapsed time between commands to extend orretract the arms. If a preselected time, such as five minutes, haslapsed since the previous command was received, the computerinstructions can instruct the processor to automatically causeretraction of the arms, if extended, or to retain the arms in aretracted position, if not extended, upon receipt of the subsequentcommand. An indication of the engagement of this safety feature can thenbe provided to the operator causing transmission of the command.

As described previously, usable operators for causing movement of therod can include, without limitation, one or more hydraulic sources, oneor more electric motors, or combinations thereof. Other sources of forceand/or motion, including pneumatic and other fluid-driven sources and/ormechanical sources are also usable. In an embodiment of the invention,electrical connections can be provided between an electrical motor andthe processor or other portion of the tool for enabling selectivetransmission of current having positive polarity, negative polarity, orcombinations thereof. Movement of the rod can be caused in a firstdirection responsive to a first polarity, and in a second directionresponsive to a second polarity, enabling selective engagement andretraction of the arms, as desired.

In a further embodiment of the invention, an addressable switch can beprovided in communication with the processor or another portion of thetool, such that the operator cannot be actuated until a preselected codeis received, thereby preventing unintentional actuation of the anchorapparatus, and/or enabling other tools along a wireline to be actuatedwithout causing actuation of the anchor apparatus.

In operation, a perforating or cutting tool, or another similar toolintended for use within a wellbore, such as a production logging tool,can be engaged with the anchor apparatus and lowered to a selectedposition within the wellbore. The rod of the anchor apparatus can thenbe moved within the anchor apparatus, as described above, such that thearms of the anchor apparatus extend to contact the internal surface ofthe wellbore. The arms can then be engaged with the wellbore, such asthrough application of an upward force to the anchor apparatus to causethe arms to protrude slightly into the interior surface of the wellbore.Pressure and other forces within the wellbore, including those causedupon actuation of the tool or those caused by production of the well,thereby fail to move the tool undesirably, due to the engagement betweenthe arms and the interior surface of the wellbore. When it is desirableto retrieve the tool and/or the anchor apparatus, the arms can bedisengaged from the interior surface of the wellbore, and the rod can bemoved in the opposite direction to permit a biasing member to return thearms to a retracted position. If it is undesirable, unsuccessful, orimpossible to actuate the operator, move the rod, and/or retract thearms, a frangible member provided with a preselected tolerance can bebroken through application of an uphole force, separating at least aportion of the anchor apparatus for retrieval.

Referring now to FIG. 1, a top portion of an anchor apparatus usablewithin the scope of the present disclosure is shown. The depictedembodiment of the anchor apparatus includes an electrical motor, inoperative association with an internal piston, which is usable to bias aplurality of arms toward an extended position. Specifically, FIG. 1depicts a top sub (10) of the anchor apparatus, which can be adapted forengagement with any manner of tool string, wireline, slickline, or othercarrier or conduit, one or more downhole tools, or other components orapparatuses, as known in the art.

The top sub (10) is shown attached to a circuit board housing (14)within which a circuit board (shown in FIG. 2) is contained, via a topsub adapter (12), which can be threaded, bolted, welded, connected usingany manner of nut, screw, rivet, or other fasteners, or otherwisesecured to the top sub (10) and/or the circuit board housing (14) in anymanner. In further embodiments of the invention, any of the top sub(10), top sub adapter (12), circuit board housing (14), or any otherportion of the anchor apparatus can be integral with one another, ratherthan separable parts.

Any manner of brass or other electrical contacts (16), for accommodatinguse of wirelines, electrical motors, and similar components, insulators(18), retaining rings, sleeves, or other retaining apparatuses (20),O-rings, liners, and/or other sealing apparatuses (22), can be disposedover, within, and/or between components of the anchor apparatus, asknown in the art, to accommodate current, and to revived sufficientsealing and/or securing of parts to maintain integrity of the apparatuswithin a wellbore environment.

Referring now to FIG. 2, FIG. 3, and FIG. 4, a second, third, and fourthportion, respectively, of the anchor apparatus of FIG. 1 is shown.During normal operations, the portion the anchor apparatus shown in FIG.2 is disposed downhole from the portion of the anchor apparatus shown inFIG. 1, and the portion of the anchor apparatus shown in FIG. 3 isdisposed downhole from the portion depicted in FIG. 2. Similarly, theportion of the anchor apparatus shown in FIG. 4 is disposed downholefrom that shown in FIG. 3.

Specifically, FIGS. 2 through 4 depict the circuit board housing (14),within which a circuit board (24) is shown. The circuit board (24) canbe secured using any number of hex screws or other fasteners (26),soldering, or other means of connection, or alternatively, the circuitboard (26) can be integral with the circuit board housing (14) or otherportion of the anchor apparatus. In use, the circuit board (24) canreceive signals, such as through a wireline (not shown) attached toand/or extending through the top sub (10, visible in FIG. 1) andadjacent portions of the apparatus. Alternatively, the circuit board(24) could receive signals from a downhole slickline memory tool,through an integral component within the anchor apparatus, orcombinations thereof. An associated processor of the circuit board (24)can thereby process received signals and cause actuation of the anchorapparatus responsive to the signals. The circuit board (24) can alsoinclude any manner of associated data storage for storing computerinstructions to control operations of the processor, such asimplementation of a safety feature to cause retraction of the arms ofthe anchor apparatus if no command is received for a selected period oftime, as described previously. Adjacent either end of the circuit board(24), a chassis (28) is shown, which can be secured using any manner ofO-ring or similar sealing apparatus (22), or other type of fastener asknown in the art. FIG. 4 also depicts a motor housing (30) within whichan electrical motor (shown in FIG. 5) is disposed, which can be securedusing any manner of sealing apparatus (22) or similar method offastening or securing known in the art.

Referring now to FIG. 5, a fifth portion of the anchor apparatus shownin FIGS. 1-4 is depicted. During normal operations, the portion of theanchor apparatus shown in FIG. 5 is disposed downhole from that shown inFIG. 4. FIG. 5 depicts an electrical motor (32) disposed within themotor housing (30). The electrical motor (32) is shown disposed adjacentto and mounted using a motor mount (34), however it should be understoodthat any manner of connection or securing known in the art can be usedto position the electrical motor (32) within the anchor apparatus.Additionally, the anchor apparatus can be understood to include anymanner of wiring, electrical contacts, connections, conductors, andinsulators, as known in the art, to enable the electrical motor (32) toreceive electrical signals through a wireline or similar conductor, aslickline memory tool, wireless and/or remote actuation, or combinationsthereof. Further, while the depicted embodiment of the anchor apparatusis shown including an electrical motor (32), it should be understoodthat in various embodiments of the invention, other operators are alsousable, including, without limitation, one or more hydraulic sources,pneumatic sources, other fluid-driven operators, mechanical sources, orcombinations thereof.

FIG. 6 depicts a sixth portion of the anchor apparatus, disposed, duringnormal operations, downhole from the portion of the anchor apparatusshown in FIG. 5. Specifically, FIG. 6 depicts the electrical motor (32)within the motor housing (30), adjacent the motor mount (34), which isshown secured within the anchor apparatus using one or more sealingapparatuses (22) or other fasteners or methods of attachment. Theelectrical motor (32) is shown operatively engaged with a drive shaft(36) via a motor attachment (38), the drive shaft being operable todrive or otherwise impart force to an internal piston (depicted insubsequent Figures) or other portion of the anchor apparatus. FIG. 6also depicts a transmission housing (40), which contains variouscomponents of a transmission system associated with the electrical motor(32).

Referring now to FIG. 7 and FIG. 8, a seventh and eight portion,respectively, of the anchor apparatus are shown, which are disposed,during normal operations, downhole from the portion of the anchorapparatus shown in FIG. 6. The motor mount (34) and additional sealingapparatuses (22) for securing the motor mount (34) are shown disposedwithin the transmission housing (40). The transmission housing (40) isshown including a screw (42) or similar pin or secured member within,which can include a lead screw in an embodiment of the invention,engaging the drive shaft (36) and positioned and/or movable using ascrew guide (44). A busing (46) coupled with a bearing (48) facilitatesrelative motion between components within the transmission housing (40),as known in the art, while a nut (50) or similar fasteners can be usedto secure fixed components within the transmission housing (40). Withinthe lower portion of the transmission housing (40), a wire guide (52), atube (54), or combinations thereof can be used to accommodate conductorsand other similar components.

Referring now to FIG. 9, a ninth portion of the anchor apparatus isshown, which can be disposed adjacent to the portion shown in FIG. 8during normal operations. The lower portion of the tube (54) is shownwithin the transmission housing (40), which engages an anchor adapter(56) at its lower end, for attachment to adjacent components of theanchor apparatus. Two o-rings or similar sealing members (22) or otherengaging members can be placed between the transmission housing (40) andthe anchor adapter (56).

Referring now to FIGS. 10 and 11, tenth and eleventh portions of theanchor apparatus are shown, which are disposed adjacent to the portionshown in FIG. 9 during normal operations. Specifically, FIGS. 10 and 11depict the lower end of the anchor adapter (56) disposed adjacent to atube (58) with an endcap (60) engaged thereto. A piston (62) is disposedadjacent to the tube (58), in operative association with an actuator(64). A plurality of arms (66) are disposed adjacent to the piston (62),each of the arms (66) being pivotally attached within the anchorapparatus via a hinge pin (72) or similar member, such that when biasedby the piston (62), the arms (66) are movable between a retractedposition within the anchor apparatus, and an extended position thatprotrudes through associated openings (68) within the body of the anchorapparatus for engagement with an interior surface of a wellbore. Thepiston (62) can be provided in operative communication with the electricmotor (32, shown in FIG. 6), such that actuation of the piston (62)using the drive shaft (36, shown in FIG. 6) of the electric motor causesaxial movement of the piston (62) within the body of the anchorapparatus. Movement of the piston (62) can engage an angled surface (70)of one or more of the arms (66), such that the arms are biased throughthe associated openings (68) into an extended position for engagementwithin the wellbore. When the piston (62) is removed from engagementwith the arms (66), a spring (76) or similar biasing member incommunication with a movable body (74) can bias the arms (66) toward aretracted position. While the number, dimensions, and configuration ofthe arms (66) can be varied depending on the specific application of theanchor apparatus, in an embodiment of the invention, the anchorapparatus can include three sets of arms of differing sizes, each set ofarms including three individual arms. For example, an embodiment of theinvention can include a first set of three arms each having a length ofabout 3.5 inches, a second set of three arms each having a length ofabout 45 inches, and a third set of three arms each having a length ofabout 5.5 inches.

FIG. 15A depicts an embodiment of the piston (62) usable within thescope of the present disclosure. While the dimensions and shape of thepiston (62) can vary, in an embodiment of the invention, the piston (62)can include a segment of pipe having a diameter of approximately 3.5inches. The piston (62) is shown having a first end (96) with a diameterslightly narrow than that of a second end (98), with a tapering shoulder(100) therebetween. The second end (98) of the piston is further shownhaving a tapered end (102) for engagement with one or more of theplurality of arms (66).

FIGS. 15B and 15C depict embodiments of arms (66), usable within thescope of the present disclosure. While the dimensions and shapes of thearms (66) can vary, the arm (66) depicted in FIG. 15B is shown having alength of approximately 4.5 inches, and the arm (66) depicted in FIG.15C is shown having a length of approximately 3.5 inches. Each arm (66)is shown having a generally angled surface (70), adapted for contactwith the tapered end (102) or other portion of the piston (62), suchthat movement of the piston (62) biases the arm (66) outward from theanchor apparatus. The arms (66) are further shown having pointed ends(104), which can include tungsten carbide and/or diamond facing orinserts, as known in the art, to facilitate penetration into an interiorsurface of a wellbore. Each arm (66) is also shown having a bore (106)or through-hole, for accommodating a hinge pin or similar member toprovide pivotal movement of the arm (66) relative to the body of theanchor apparatus.

Referring now to FIG. 12, a twelfth portion of the anchor apparatus isshown, which can be disposed adjacent to the portion shown in FIG. 11during normal operations. The lower ends of the spring (76) and actuator(64) are shown adjacent to a locator body (78) and a shear ring (80) orsimilar frangible member, such as a screw or pin. Prior to lowering theanchor apparatus into the wellbore, the shear ring (80) or similarfrangible member can be provided with a selected tolerance, such thatwhen retraction of the arms (66, depicted in FIGS. 10-11) is undesired,unsuccessful, or impossible, a sufficient force provided to the anchorapparatus can shear the shear ring (80), enabling at least partialretrieval of the anchor apparatus and the wireline or other conduit usedto lower the apparatus into the wellbore.

FIG. 12 also depicts a series of packing or spacing elements (82), whichcan include any manner nuts, spacers, or similar elements known in theart, which facilitate engagement with lower portions of the anchorapparatus. O-rings or similar sealing members (22) can be providedadjacent to and/or between any of the spacing elements (82).

Referring now to FIGS. 13 and 14, a thirteenth and fourteenth portion ofthe anchor apparatus, respectively, are shown, which can be disposedadjacent to the portion shown in FIG. 12 during normal operations.Specifically, the lower portion of the anchor apparatus is shown, whichincludes a lower adapter (88) engaged with the remainder of the anchorapparatus, having one or more O-rings or similar sealing members (22)disposed thereon. A rubber boot (84) or similar insulating member isshown adjacent to the lower adapter (88), which can be secured by acrimped contact (86) or similar conductive member. A plunger (90) isshown engaged at the lowest point of the anchor apparatus, which can beaxially movable via a spring (92) or similar biasing member. Any mannerof contacts (16) and/or insulators (18) are usable to electronicallyconnect or isolate the plunger (90) and/or the lower adapter (88) asknown in the art. Similarly, one or more sealing members (22), such asO-rings, are shown, in addition to a retainer ring (94), are shownsecuring the plunger (90) and lower adapter (88).

In use, a tool can be secured to the anchor apparatus of FIGS. 1-14, andthe tool and anchor apparatus can be lowered to a selected positionwithin a wellbore. The electrical motor (32) can be actuated, such asthrough use of a wire line to communicate a signal from the surface tothe circuit board (24), or through use of a slickline memory toolprovided in communication with the electrical motor, causing the driveshaft (36) of the electrical motor (32) to impart movement to the piston(62) within the body of the apparatus. Movement of the piston (62)biases the arms (66) into an extended position by pivoting the armsthrough the openings (68) in the body of the apparatus using the hingepins (72) or similar movable members. The arms (66) can then be engagedwith an interior surface of the wellbore, such as through application ofan uphole force applied from the surface, which can cause the tips ofthe arms (66) to protrude slightly into the wellbore surface. Engagementbetween the arms (66) and the wellbore prevents undesired movement ofthe anchor apparatus and attached tool responsive to any changes inpressure or other forces within the wellbore, including pressure changescaused through actuation of the tool.

To remove the anchor apparatus and/or the tool from the wellbore, thearms (66) can be disengaged from the interior surface of the wellboreand permitted to retract through the openings (68) into the body of theapparatus by communicating a second signal, to cause the electricalmotor (32) to move the piston (62) in the opposite direction. Movementof the piston (62) away from the arms (66) permits springs (76) orsimilar biasing members to return the arms (66) to the retractedposition. In selected embodiments of the invention, movement of thepiston (62) in a first selected direction can be caused using currenthaving a first polarity, while movement of the piston (62) in thereverse direction can be caused using current having a second polarity.Alternatively, the shear ring (80) or similar frangible member can bebroken, such as through application of an uphole force in excess of thetolerance of the shear ring (80), to enable removal of the apparatusfrom the wellbore.

In an embodiment of the invention, a processor in association with thecircuit board (24) can be provided in operative communication withcomputer instructions that determine the amount of time that has lapsedbetween commands received by the processor. If a selected interval oftime, such as five minutes, has lapsed, receipt of a command by thecircuit board (24) can cause automatic movement of the piston (62) toretract the arms (66), if the arms (66) are disposed in an extendedposition, or alternately, receipt of a command by the circuit board (24)can cause no movement of the piston (62), if the arms are in theretracted position. In a further embodiment of the invention, thecircuit board (24) can include an addressable switch, such that signals,commands, and/or current transmitted to the anchor apparatus will notcause actuation of the electrical motor (32) and/or movement of thepiston (62) until activation of the addressable switch using apreselected address and/or code.

Referring now to FIG. 16A a diagrammatic view of an embodiment of ananchor apparatus (204) usable within the scope of the present disclosureis shown disposed within a wellbore conduit (200). It is to beunderstood that the wellbore conduit (200) can include any mannerearthen or rock borehole, or any manner of drillpipe, casing, or othertubular member, as known in the art. Within the wellbore conduit (200),the anchor apparatus (204) is shown engaged with a downhole tool (202),which FIG. 16A depicts as a perforating tool. The anchor apparatus (204)includes a plurality of arms (206), which are shown disposed within itsbody. A piston (208), driven by a drive shaft (210) of a motor orsimilar operator, is useable to contact and bias the plurality of arms(206) outward once the anchor apparatus (210) and downhole tool (202)have been lowered or raised to a desired position within the wellboreconduit (200).

FIG. 16B depicts the anchor apparatus (204) of FIG. 16A engaged with thewellbore conduit (200). Actuation of the motor or other operator cancause the drive shaft (210) to move the piston (208) in a downholedirection. Contact between the piston (208) and the arms (206) biasesthe arms (206) in an outward direction to contact the interior surfaceof the wellbore conduit (200). The engagement between the arms (206) andthe wellbore conduit (200) prevents undesired movement of the anchorapparatus (204) and the attached downhole tool (202) responsive todownhole forces, including those generated through actuation of thedownhole tool (202). When it is desired to remove the downhole tool(202) and/or the anchor apparatus (204) from the wellbore conduit (200),the drive shaft (210) can be used to retract the piston (208) in anuphole direction, permitting the arms (206) to return to the positionshown in FIG. 16A, such as through use of a spring or other biasingmember.

Embodiments of the present invention thereby provide anchor apparatusesand methods for anchoring and/or maintaining a position of a tool withina wellbore that provide improved reliability and simplicity overconventionally available devices, can incorporate use of back-up methodsof removal, and can further include automatic safety features forpreventing attempted retrieval of the anchor apparatus when engaged withthe interior surface of a wellbore.

While the present invention has been described with emphasis on certainembodiments, it should be understood that within the scope of theappended claims, the present invention can be practiced other than asspecifically described herein.

1. An anchor apparatus for maintaining a position of a tool within awellbore, the anchor apparatus comprising: a tubular body comprising arod movable within the tubular body and at least one connection forengagement with the tool; an operator in communication with the rod,whereby actuation of the operator causes movement of said rod between afirst position and a second position; and a plurality of arms pivotallysecured to the tubular body, wherein the plurality of arms are pivotallymovable between a retracted position and an extended position forengaging an interior surface of the wellbore, wherein the plurality ofarms are in operative communication with a biasing member that biasesthe plurality of arms toward the retracted position, wherein movement ofsaid rod from the first position to the second position causes theplurality of arms to pivot to the extended position, and whereinengagement between the plurality of arms and the interior surface of thewellbore temporarily anchors the tool within the wellbore.
 2. The anchorapparatus of claim 1, further comprising a frangible member disposed atan end of the plurality of arms, wherein the frangible member comprisesa portion that is provided with a preselected tolerance that exceeds afirst force within the wellbore and is less than a second forcesufficient to damage the plurality of arms, and wherein the portion ofthe frangible member breaks upon application of a force greater or equalto the preselected tolerance for enabling removal of the anchorapparatus from the wellbore.
 3. The anchor apparatus of claim 1, furthercomprising a processor in communication with the operator and computerinstructions for instructing the processor to receive a command andcause actuation of the operator to move said rod between the firstposition and the second position responsive to the command.
 4. Theanchor apparatus of claim 3, wherein the computer instructions furtherinstruct the processor to cause actuation of the operator to move saidrod from the second position to the first position to permit the biasingmember to pivot the plurality of arms to the retracted positionresponsive to the command if no command has been received for apreselected length of time.
 5. The anchor apparatus of claim 1, whereinthe operator comprises a hydraulic power source.
 6. The anchor apparatusof claim 3, wherein the operator comprises an electrical motor.
 7. Theanchor apparatus of claim 6, wherein the electrical motor furthercomprises electrical connections in communication with the processor,wherein the electrical connections are adapted to transmit currenthaving positive polarity, negative polarity, or combinations thereof,and wherein the computer instructions further instruct the processor tocause actuation of the electrical motor to move said rod from the firstposition to the second position responsive to current having a firstpolarity, and to cause actuation of the electrical motor to move saidrod from the second position to the first position responsive to currenthaving a second polarity.
 8. The anchor apparatus of claim 6, furthercomprising an addressable switch in communication with the processor,wherein the addressable switch enables actuation of the operator after apreselected code is received by the addressable switch, the processor,or combinations thereof.
 9. The anchor apparatus of claim 1, wherein thetool comprises a perforating apparatus, a cutting apparatus, anisolation apparatus, or a logging apparatus.
 10. The anchor apparatus ofclaim 1, wherein the plurality of arms engage the interior surface ofthe wellbore with a tolerance greater than or equal to a force resultingfrom actuation of the tool, wherein the tool thereby maintains theposition within the wellbore.
 11. A method for maintaining a position ofa tool within a wellbore, the method comprising the steps of: engagingthe tool with an anchor apparatus and lowering the tool and anchorapparatus to the position within the wellbore; moving a rod of theanchor apparatus to cause a plurality of arms in operative associationwith said rod to contact an internal surface of the wellbore; engagingthe plurality of arms with the internal surface of the wellbore, whereinthe engagement between the plurality of arms and the internal surfacecomprises a tolerance; actuating the tool, producing the well, orcombinations thereof, wherein the actuation of the tool, the productionof the well, or combinations thereof causes a force, and wherein thetolerance of the engagement between the plurality of arms and theinternal surface exceeds the force thereby maintaining the tool in theposition within the wellbore.
 12. The method of claim 11, furthercomprising the steps of: providing a frangible member of the anchorapparatus with a preselected tolerance that exceeds the force caused byactuation of the tool and is less than a second force sufficient todamage the plurality of arms; breaking the frangible member by applyinga force to the frangible member greater or equal to the preselectedtolerance, thereby separating at least a portion of the anchor apparatusfrom the tool; and removing said at least a portion of the anchorapparatus from the wellbore.
 13. The method of claim 11, furthercomprising the steps of: disengaging the plurality of arms from theinner surface of the wellbore; and moving said rod to permit a biasingmember of the anchor apparatus in operative association with theplurality of arms to cause the plurality of arms to withdraw from theinner surface of the wellbore.
 14. The method of claim 11, wherein thestep of moving said rod of the anchor apparatus comprises transmitting acommand to a processor in communication with an operator in associationwith said rod, wherein the processor causes actuation of the operator tocause movement of said rod responsive to the command.
 15. The method ofclaim 13, wherein the step of moving said rod to cause the plurality ofarms to contact the interior surface comprises communicating electricalpower having a first polarity to cause movement of said rod in a firstdirection, and wherein the step of moving said rod to permit the biasingmember to cause the plurality of arms to withdraw the inner surfacecomprises communicating electrical power having a second polarity tocause movement of said rod in a second direction.
 16. The method ofclaim 11, further comprising the step of transmitting a preselected codeto an addressable switch in communication with said rod, wherein theaddressable switch enables actuation of said rod after the preselectedcode is received.
 17. The method of claim 11, wherein the tool comprisesa cutting or perforating apparatus, wherein the step of actuating thetool causes pressure from the wellbore, and wherein the tolerance of theengagement between the plurality of arms and the internal surface of thewellbore exceeds the pressure, thereby maintaining the tool in theposition with the wellbore.
 18. The method of claim 14, furthercomprising the steps of: permitting a preselected length of time topass; and transmitting a command to the processor, wherein computerinstructions in communication with the processor instruct the processorto cause the plurality of arms to withdraw from the inner surface of thewellbore when the command is received after the preselected length oftime has passed.
 19. An anchor apparatus for maintaining a position of atool within a wellbore, the anchor apparatus comprising: a tubular bodyengaged with the tool, wherein the tubular body comprises a rod movablewithin the tubular body; an operator in communication with said rod,whereby actuation of the operator causes movement of said rod between afirst position and a second position; a plurality of arms pivotallysecured to the tubular body, wherein the plurality of arms are pivotallymovable between a retracted position and an extended position forengaging an interior surface of the wellbore, wherein the plurality ofarms are in operative communication with a biasing member that biasesthe plurality of arms toward the retracted position, wherein movement ofsaid rod from the first position to the second position causes theplurality of arms to pivot to the extended position, and whereinengagement between the plurality of arms and the interior surface of thewellbore temporarily anchors the tool within the wellbore; and aprocessor in communication with the operator and computer instructionsfor instructing the processor to receive a command and cause actuationof the operator to move said rod between the first position and thesecond position responsive to the command, wherein the computerinstructions further instruct the processor to cause actuation of theoperator to move said rod from the second position to the first positionto permit the biasing member to pivot the plurality of arms to theretracted position responsive to the command if no command has beenreceived for a preselected length of time.
 20. The anchor apparatus ofclaim 19, further comprising a frangible member disposed at an end ofthe plurality of arms, wherein the frangible member comprises a portionhaving a preselected tolerance that exceeds a first force within thewellbore and is less than a second force sufficient to damage theplurality of arms, and wherein the portion of the frangible memberbreaks upon application of a force greater or equal to the preselectedtolerance for enabling removal of the anchor apparatus from thewellbore.
 21. The anchor apparatus of claim 19, wherein the operatorcomprises a hydraulic power source.
 22. The anchor apparatus of claim19, wherein the operator comprises an electrical motor.
 23. The anchorapparatus of claim 22, wherein the electrical motor further compriseselectrical connections in communication with the processor, wherein theelectrical connections are adapted to transmit current having positivepolarity, negative polarity, or combinations thereof, and wherein thecomputer instructions further instruct the processor to cause actuationof the electrical motor to move said rod from the first position to thesecond position responsive to current having a first polarity, and tocause actuation of the electrical motor to move said rod from the secondposition to the first position responsive to current having a secondpolarity.
 24. The anchor apparatus of claim 19, further comprising anaddressable switch in communication with the processor, wherein theaddressable switch enables actuation of the power source after apreselected code is received by the addressable switch, the processor,or combinations thereof.
 25. The anchor apparatus of claim 19, whereinthe tool comprises a perforating apparatus, a cutting apparatus, or anisolation apparatus.
 26. The anchor apparatus of claim 19, wherein theplurality of arms engage the interior surface of the wellbore with atolerance greater than or equal to a force resulting from actuation ofthe tool, wherein the tool thereby maintains the position within thewellbore.